JP2007530982A - Electro-optical variable optical filter - Google Patents

Abstract

The present invention provides a method and apparatus for filtering an optical signal. The method includes receiving at least one input optical signal, forming first and second optical signals using the at least one input optical signal, and modifying at least one portion of the first optical signal using a plurality of non-waveguiding electro-optic phase adjusters. The method also includes forming an output optical signal by combining the first optical signal, including the at least one modified portion of the first optical signal, with the second optical signal.

Description

Field of Invention

  The present invention relates generally to optical transmission mechanisms, and more particularly to electro-optical variable optical filters for use in optical transmission mechanisms.

  Photonics, the use of light to store, transmit and / or process information, is rapidly penetrating into the market for everyday and advanced technology products. For example, optics is the transmission medium of choice for many urban and rural networks. In order to maintain bandwidth and operate various components of the optical transmission network together, the optical transmission network can typically dynamically equalize power to the network wavelength, or frequency, channel. Use advanced light filters. Typical optical filters that dynamically equalize power based on wide spectral characteristics include Mach-Zehnder filters, acoustic-light filters, holograms, and micro-mechanical drive mirrors. Typical optical filters that dynamically equalize power for each channel include a demultiplexer, a programmable attenuator array, and a multiplexer.

  An optical filter can include one or more waveguides for optical transmission and one or more elements capable of adjusting the phase of light propagation in the waveguides. In traditional phasing waveguides, Joule heaters are placed near the waveguide and used to change the temperature of the optical waveguide. Since the effective refractive index of the optical waveguide varies depending on the temperature of the waveguide, changing the temperature changes the optical path length of the waveguide, thereby changing the phase of light traveling in the optical waveguide. Thermo-optical phase adjustment is used with optical attenuators, spectral selective filters, interferometers, and the like. For example, Douer (US Pat. No. 6,212,315) describes a channel power equalizer that uses thermo-optical phase adjustment with multiple phase shifters.

  However, traditional methods of changing the light propagation phase in a waveguide, including thermal-optical phase adjustment, may not be well suited for spectral filtering applications. The sensitivity of temperature dependent phase control devices may be limited by the relatively small thermo-optic coefficient of silica. Other materials may exhibit greater thermo-optic coefficients, but these materials may be difficult to form into low loss single mode waveguides. Furthermore, the phase-controlled thermo-optic method cannot respond quickly enough to be tightly integrated with other electronic devices in the optical transmission network.

Furthermore, an optical filter is often formed in a semiconductor-based waveguide, and thermal crosstalk between multiple temperature-dependent phase control devices formed in the same semiconductor-based waveguide is temperature-dependent. The accuracy, fineness, and control of the phase controller may be reduced. As a result, a phase control device with less temperature dependency can be included in a single semiconductor substrate waveguide. Thermal crosstalk may reduce the range of the phase expression of the temperature dependent phase controller. Lowering the phase display range can be at least partially compensated by increasing the temperature range applied to the phase controller, but increasing the temperature range typically increases the power consumption of the device accordingly. To do. Furthermore, the polarization independence of the orthonormal mode may be reduced by thermal crosstalk.
US Pat. No. 6,212,315

  In one aspect of the invention, a method for filtering an optical signal is provided. The method receives at least one input optical signal, uses the at least one input optical signal to form first and second optical signals, and uses a plurality of non-guided electro-optical phase adjusters And modifying at least a portion of the first optical signal. The method also includes combining the first optical signal including at least one modified portion of the first optical signal with the second optical signal to form an output optical signal.

  As another aspect of the present invention, an apparatus is provided. The apparatus is optically coupled to an optical demultiplexer, a plurality of non-waveguide electrical-optical phase adjustment devices optically coupled to the optical demultiplexer, and a plurality of non-waveguide electrical-optical phase adjustment devices. An optical multiplexer coupled to the.

  In yet another embodiment of the invention, an electro-optical variable optical filter is provided. The electro-optic variable optical filter includes a first optical transmission medium, a second optical transmission medium, and a first optical coupler for coupling portions of the first and second optical transmission media. The electro-optical variable optical filter includes an optical demultiplexer coupled to the second optical transmission medium, a plurality of non-waveguide electro-optical phase adjustment devices optically coupled to the optical demultiplexer, And an optical multiplexer optically coupled to a plurality of non-waveguide electro-optical phase adjusting devices. The electro-optical variable optical filter further comprises a third optical transmission medium optically coupled to the optical multiplexer and a second optical coupler for coupling portions of the second and third optical transmission media. Include.

  The present invention can be understood by the following description with reference to the accompanying drawings (similar numbers in the figures indicate similar parts).

  While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown in the drawings and will herein be described in detail. However, this description of specific embodiments does not limit the invention to the specific form disclosed herein, but on the contrary, all modifications that fall within the spirit and scope of the invention as defined in the claims, Needless to say, equivalents and alternatives are included.

  Exemplary embodiments of the present invention are described below. For the purpose of clarity, not all features of a realistic implementation are described herein. Of course, in all such realistic implementation deployments, making specific decisions for many implementations to achieve a developer's special goals, such as equipment and tasks that vary from implementation to implementation It is necessary to follow the restrictions on Moreover, although the development efforts are complex and time consuming, the benefits of the present disclosure will be appreciated for such developments typically performed by those skilled in the art.

  FIG. 1A conceptually illustrates an exemplary first embodiment of a dynamic and chromatically variable transmission device, such as a dynamic gain equalization filter 100. The following description is made with respect to the embodiment of the dynamic gain equalization filter 100 shown in FIGS. 1A and 1B, but the invention is not limited thereto. In another embodiment, the variable transmittance device 100 may be one of various optical elements known to those skilled in the art. For example, the variable transmittance apparatus 100 may be a channel equalizer, a Mach-Zehnder filter, a Michelson interferometer, or the like for controlling channel power in the wavelength division multiplexing system.

  The first exemplary embodiment of the dynamic gain equalization filter 100 includes first and second optical transmission media 101 and 102. In one embodiment, the first and second optical transmission media 101, 102 are waveguides. Although not necessary for the practice of the present invention, the first optical signal may enter the dynamic gain equalization filter 100 through the first port 105 in the non-reciprocal device 110. In one embodiment, non-reciprocal device 110 is a circulator 101 that can be formed using a material having a high Verde constant, as will be apparent to those skilled in the art.

  The non-reciprocal device 110 transmits the first optical signal to the waveguide 101 and then enters the dynamic gain equalization filter 100 through the first port 115 in the first optical coupler 120. Can be optically coupled. However, as another embodiment, the first optical signal may be passed through the dynamic gain equalization filter 100 without passing through the non-reciprocal device 110. Although not necessary for the practice of the present invention, the second optical signal propagating along the waveguide 102 enters the dynamic gain equalization filter 100 through the second port 125 in the first optical coupler 120. be able to. In one embodiment, the first optical signal and, if present, the second optical signal are wavelength division multiplexed optical signals.

  The first optical coupler 120 can split and / or combine the first and second optical signals to form two signal components, which are the upper and lower arms 125 of the waveguides 101, 102. , 130 respectively. For example, when the second optical signal is not supplied to the dynamic gain equalization filter 100 via the waveguide 102, the first optical coupler 120 converts the first signal into two signal components √R and j√1-R. Where R is the division ratio of the first optical coupler 120. The two signal components √R and j√1-R are transmitted to the upper and lower arms 125, 130, respectively. In one embodiment, at least some of the upper and lower arms 125, 130 are waveguides. For example, the upper arm 125 may be a waveguide. In another example, the first portion 133 (1-2) of the lower arm 130 may be a waveguide.

  The first portion 133 (1) of the lower arm 130 is optically coupled to the optical demultiplexer 135 as desired. In one embodiment, the optical demultiplexer 135 receives the signal component j√1-R from the lower arm 125 and corresponds the signal component j√1-R to a plurality of selected frequencies and / or wavelength bands. Divide into parts. For example, the signal component j√1-R has a bandwidth of 60 nm and is demultiplexed into 60 parts having a bandwidth of 1 nm. However, in another embodiment, various devices well known to those skilled in the art are used to divide the signal component j√1-R into portions corresponding to a plurality of selected frequencies and / or wavelength bands. can do. These devices include, but are not limited to, optical dividers, prisms, gratings, and the like.

  The optical demultiplexer 135 supplies the portion of the signal component j√1-R to a corresponding plurality of electro-optical phase adjustment devices 140 that are optically coupled to the optical demultiplexer 135. As will be apparent to those skilled in the art, the number of electro-optical phase adjustment devices 140 is selected depending on the design. Thus, although three electro-optical phase adjusters 140 are shown in FIG. 1, other embodiments of the present invention include more or fewer electro-optical phase adjusters 140. Also good.

  In a first exemplary embodiment of the dynamic gain equalization filter 100 shown in FIG. 1A, a plurality of electro-optical phase adjustment devices 140 are optically coupled to a mirror 145. Upper arm 125 is also optically coupled to mirror 145. Although not necessary for the practice of the present invention, the wave plate 150 is placed adjacent to the mirror 145 and propagates through the upper arm 125 and the electro-optical phase adjuster 140 respectively. 1-R may be reflected from mirror 145 after passing through wave plate 150. For example, a quarter wave plate 150 can be placed between the mirror, the upper arm 125 and the electro-optical phase adjustment device 140. By incorporating the quarter wave plate 150, the birefringence in the portion of the signal component j√1-R can be reduced or zero.

  The optical path lengths of the upper and lower arms 125, 130 are approximately equal in certain embodiments. For example, the optical path length of the lower arm 130, including the upper arm 125 and the optical demultiplexer 135, the electro-optical phase adjustment device 140, and the wave plate 150, may be the first and second optical signals (if present). And within a few wavelengths. As will be discussed in detail below, by controlling or adjusting the effective optical path length of the electro-optical phase adjusting device 140 and the optical path length of the lower arm 130, the signal component j√1-R is It can be corrected. In one embodiment, one or more effective optical path lengths of the electro-optical phase adjuster 140 can be varied such that one or more relative phase differences between the portions of the signal component j√1-R are introduced. it can. For example, a phase difference π / 4 can be introduced between two parts of the signal component j√1-R.

  After the two signal components √R and j√1-R are reflected from the mirror 145, they are transmitted back to the first optical coupler 120 along substantially the same optical path. As a result, one or more relative phase differences between portions of the signal component j√1-R introduced by the electro-optical phase adjustment device 140 may be approximately doubled. For example, if one of the electro-optical phase adjustment devices 140 introduces a phase difference of about π / 4 between two parts of the signal component j√1-R during one pass, the signal component j√1 A total phase difference of about π / 2 can be introduced between the two parts of -R.

  As a first exemplary embodiment, the optical demultiplexer 135 can also function as an optical multiplexer for the reflected portion of the signal component j√1-R. For example, the optical demultiplexer 135 can be integrated with the reflected portion of the signal component j√1-R to form a modified signal component j√1-R. The first optical coupler 120 can combine and / or split the signal component √R and the modified signal component j√1-R to form an output signal. For example, the signal component √R and the modified signal component j√1-R can interfere destructively and / or constructively to form a filtered output signal. In one embodiment, this filtered output signal can be provided to non-reciprocal device 110 and then exit the dynamic gain equalization filter via second port 155. However, as discussed above, the non-reciprocal device 110 is used as desired and may be omitted in other embodiments of the invention.

  FIG. 1B shows a second exemplary embodiment of the dynamic gain equalization filter 100. In a second exemplary embodiment of the dynamic gain equalization filter 100, a plurality of electro-optical phase adjustment devices 140 are optically coupled to the optical multiplexer 160. A portion of the signal component j√1-R, including all modified portions, can be supplied to the optical multiplexer 160. In one implementation, the optical multiplexer 160 may combine these portions to form a modified signal component j√1-R.

  In a second exemplary embodiment of the dynamic gain equalization filter 100, the signal component √R propagating through the upper and lower arms 125, 130, respectively, and the modified signal component j√1-R are: The second optical coupler 165 can be split and / or combined with the signal component √R and the modified signal component j√1-R. For example, the signal component √R and the modified signal component j√1-R can interfere destructively and / or constructively to form a filtered output signal. In one embodiment, the first and second optical couplers 120, 165 have the same split ratio R, but this is not necessary for the practice of the present invention. Further, the second optical coupler 165 can be omitted in various alternative embodiments of the present invention.

   The optical path lengths of the upper and lower arms 125, 130 are approximately equal in certain embodiments. For example, the optical path length of the lower arm 130, which includes the upper arm 125, and the optical demultiplexer 135, the electro-optical phase adjustment device 140, and the optical multiplexer 145, includes first and second optical signals (present In the case of a few wavelengths. As will be discussed in detail below, by controlling or adjusting the effective optical path length of the electro-optical phase adjusting device 140 and the optical path length of the lower arm 130, the signal component j√1-R is It can be corrected. In one embodiment, one or more effective optical path lengths of the electro-optical phase adjuster 140 can be varied such that one or more relative phase differences between the portions of the signal component j√1-R are introduced. it can. For example, a phase difference π / 4 can be introduced between two parts of the signal component j√1-R.

  In each of the first or second exemplary embodiments shown in FIGS. 1A and 1B, one or more components of the dynamic gain equalization filter 100 are combined into a single flat waveguide platform (not shown). ) Can be formed on. For example, the optical demultiplexer 135, the plurality of electro-optical phase adjustment devices 140, and the mirror 150 or the optical multiplexer 160 can be formed on a flat waveguide platform. In other various embodiments, a flat waveguide platform can be formed of a polymer, silica formed on silicon, a semiconductor, or similar material.

  Due to the fast response time of the plurality of electro-optical phase adjusters 140, at least in part, the two embodiments of the dynamic gain equalization filter 100 shown in FIGS. 1A and 1B are tightly integrated with other electronic devices. can do. Furthermore, the thermal crosstalk between multiple electro-optical phase adjusting devices 140 can be reduced, for example, more than a plurality of thermo-optical phase adjusting devices, so that the electro-optical phase adjusting device 140 can be formed on a single platform. The number can be increased. The electro-optical phase adjustment device 140 can increase the range of phase display and reduce power consumption, for example, as compared to a plurality of thermal-optical phase adjustment devices.

  FIG. 2 conceptually illustrates a plurality of electro-optical phase adjustment devices 140 according to one embodiment of the present invention. As described above, in one embodiment, the signal component j√1-R is supplied to the optical demultiplexer 135 via the first portion 133 (1) of the lower arm 130. In the illustrated embodiment, the optical demultiplexer 135 is optically coupled to a plurality of optical transmission media, such as the waveguide 200, which are located near the corresponding plurality of slots 210. can do. In one embodiment, the end of the waveguide 200 can be placed near the slot 210, so that the waveguide 200 is optically coupled to the slot 210 and the portion of the signal component j√1-R is The slot 210 can be supplied. For example, each of the waveguides 200 is a part of a signal component j√1-R having a selected wavelength (or frequency) and a wavelength (or frequency) within a band, corresponding to a plurality of slots 210. Can be supplied to.

  An electro-photoactive phase adjusting element 220 can be disposed in at least a portion of the slot 210. In one embodiment, the electro-photoactive phase adjusting element 220 may be an electro-photoactive material that can be disposed in the slot 210, such as a liquid crystal, a polymer dispersed liquid crystal, a birefringent material, and the like. However, any desired type of electro-optically active phase adjusting element 220 can be used. For example, in another embodiment, the electro-photoactive phase adjusting element 220 may be a silicon substrate having an opening filled with an electro-photoactive material. In this alternative embodiment, the electro-photoactive phase adjustment element 220 can be formed separately and subsequently inserted into the electro-photoactive phase adjustment device 140.

  One or more electrodes 230 are placed near the slot 210. In the illustrated embodiment, two electrodes 230 are disposed on at least a portion of the waveguide 200 (shown in dashed lines) near the slot. However, the present invention is not so limited. In another embodiment, more or fewer electrodes 230 can be placed near the slot 210. Further, in another embodiment, at least a portion of the electrode 230 can be disposed in the slot 210.

  The electrode 230 is connected to the control device 240 via the line 250. In various alternative embodiments, the line 250 may be a wire, a conductive trace, or the like. Controller 240 can provide selected signals, such as voltage and / or current, to electrode 230. As will be apparent to those skilled in the art, the signal provided by the controller 240 can be used to change the optical path length of the electro-optically active phase adjusting element 220. For example, an electric field can be created by applying a voltage to one or more of the electrodes 230, and at least a portion of the electric field can penetrate into the slot 210. By changing the strength of the signal, eg, voltage, the amplitude and / or direction of the electric field can be changed, thereby changing the optical path length of the electro-photoactive phase adjusting element 220.

  The phase of one or more portions of the signal component j√1-R can be modified when the portion of the signal component j√1-R propagates through the electro-photoactive phase adjusting element 220. In one embodiment, the relative phase difference is provided to the signal component j√1 by supplying different signals to electrodes 230 located near the slot 210 corresponding to the appropriate portion of the signal component j√1-R. It can be introduced between the -R moieties. For example, the optical path length of the slot 210 corresponding to the first part of the signal component j√1-R is equal to the optical path length of the slot 210 corresponding to the second part of the signal component j√1-R and the signal component j√1-R. Introducing a relative phase difference between the two parts of the signal component j√1-R by varying the intensity of the signal supplied to the corresponding slot 210 so that it differs by about a quarter of the wavelength of be able to.

  Another plurality of optical transmission media, such as waveguide 260, may be placed in the vicinity of slot 210. In one embodiment, the end of the waveguide 260 is coupled to the slot 210 so that the waveguide 260 is optically coupled to the slot 210 and can receive a portion of the signal component j√1-R from the slot 210. It can be arranged in the vicinity. In one embodiment, a portion of the waveguide 260 (shown in dashed lines) can be disposed under one or more electrodes 230. In a first exemplary embodiment of the dynamic gain equalization filter 100 shown in FIG. 1A, the waveguide 260 can be optically coupled to the mirror 145 and / or the wave plate 150. Alternatively, in a second exemplary embodiment of the dynamic gain equalization filter 100 shown in FIG. 1B, the waveguide 260 is divided into portions of the signal component j√1-R as described above, and / or It can be optically coupled to a multiplexer 160 that can be combined.

  Slot 210 and electro-optically active phase adjusting element 220 are non-waveguide in one embodiment. Accordingly, waveguide elements, such as waveguides 200, 260, may be included in the plurality of electro-optical phase adjustment devices 140, hereinafter the electro-optical phase adjustment device 140 will be referred to as “non-waveguide” electrical. Called optical phase adjuster 140.

  FIG. 3 conceptually illustrates a perspective view of one embodiment of the electro-optical phase adjustment device 140. In the illustrated embodiment, one or more waveguide portions 305 (1-2) are formed in a dielectric layer commonly referred to in the art as a cladding layer 310 formed on a semiconductor substrate 320, eg, silicon. Is formed. Of course, the shape of the electro-optical phase adjustment device 140 is an example, and in another embodiment, the electro-optical phase adjustment device 140 may include other components not shown in FIG.

  The waveguide portion 305 (1-2) shown in the illustrated embodiment is formed from a material having a refractive index greater than that of the cladding layer 310. For example, the waveguide portion 305 (1-2) is formed from undoped silica with a refractive index of about 1.4557, and the cladding layer 310 is doped with a refractive index of about 1.445. Alternatively, it can be formed from undoped silica. In another embodiment, the waveguide portion 305 (1-2) and the cladding layer 310 can be formed from any desired material. In one embodiment, the cladding layer 310 includes at least a portion of a lower cladding layer (not shown) and at least a portion formed in a region 315 below the waveguide portion 305 (1-2), An upper cladding layer (not shown) formed in the area 320 above the waveguide portion 305 (1-2) may be included. In one embodiment, the upper and lower cladding layers may not have the same refractive index. For example, the upper cladding layer may have a refractive index of about 1.4448 and the lower cladding layer may have a refractive index of about 1.4451.

  A slot 330 is cut into the cladding layer 310 such that the end of the waveguide portion 305 (1-2) is near the slot 330. However, in another embodiment, the end of the waveguide portion 305 (1-2) may not be near the slot 330. For example, a portion of the waveguide portion 305 (1-2) may be near the slot 330 and the end of the waveguide portion 305 (1-2) may be located away from the slot 330. In one embodiment, the evanescent field amplitude due to the signal propagating in the waveguide section 305 (1-2) at the lateral edge 350 (1-2) of the slot 330 is less than the peak value of −40 dB. Cut the slot 330. However, the exact location of the slot 330 and the desired evanescent field amplitude at the lateral edge 350 (1-2) are a matter of design choice. In addition, although the slot 330 is shown as a rectangle in FIG. 3, the geometric structure of the slot 330 is designed to take into account various geometric cross-sectional shapes and cross-sectional shapes that vary along their length, It is a matter to choose.

  FIG. 4 illustrates one embodiment of an exemplary method for filtering an optical signal using, for example, the dynamic gain equalization filter 100 shown in FIGS. 1A and 1B. The method of the illustrated embodiment includes receiving (at 400) at least one input optical signal. The at least one input optical signal is then used to form first and second optical signals (at 410). For example, the optical coupler 110 shown in FIGS. 1A and 1B can use this input optical signal to form two signal components √R and j√1-R. As discussed in detail above, a plurality of electro-optical phase adjusters, such as the electro-optical phase adjuster 140 shown in FIGS. 1A and 1B, can be used to modify at least a portion of the first optical signal. (At 420). The first optical signal including at least one modified portion of the first optical signal can then be combined with the second optical signal to form an output optical signal (at 430).

  By using one or more embodiments of the dynamic gain equalization filter 100 including the electro-optical phase adjustment device 140, as discussed in detail above, the accuracy of the dynamic gain equalization filter 100, Fineness and control can be increased over, for example, a thermal-optical phase control device. For example, a number of electro-optical phase adjustment devices 140 can be included in the dynamic gain equalization filter 100 formed on a single semiconductor substrate. The range of phase display of the electro-optical phase adjuster 140 can be increased without correspondingly increasing the power consumption of the device. The polarization independence of the positive standard mode of the signal propagating through the dynamic gain equalization filter 100 can also be improved.

  In addition, future developments in adaptive filters, such as variable transmission device 100, will further increase the examples of signaling designed to be used, at least in part, for access and urban networks, and transmission key elements. It can be accelerated by refining. The present invention could broaden their range of applications much more, possibly in conjunction with other developments that are foreseen and unforeseen. In particular, due to the higher definition and lower power consumption, this approach will be well adopted for highly functional assembly structures in access and urban networks, and transmission key elements.

FIG. 2 conceptually illustrates two exemplary embodiments of a dynamic and chromatic variable transmission device, such as a dynamic gain equalization filter. FIG. 2 conceptually illustrates two exemplary embodiments of a dynamic and chromatic variable transmission device, such as a dynamic gain equalization filter. FIG. 2 conceptually illustrates a plurality of electro-optical phase adjusting devices that can be used in the dynamic and chromatic variable transmittance devices shown in FIGS. 1A and 1B. FIG. 3 conceptually illustrates a perspective view of one embodiment of the electro-optical phase adjusting device shown in FIG. 2. 1A and 1B illustrate one embodiment of an exemplary method for filtering an optical signal using the dynamic and chromatically variable transmittance apparatus shown in FIGS. 1A and 1B.

Claims (46)

A method of filtering an optical signal,
Receiving at least one input optical signal;
Forming the first and second optical signals using the at least one input optical signal;
Using a plurality of non-waveguided electro-optical phase adjustment devices to modify at least a portion of the first optical signal and to include the first optical signal including at least one modified portion of the first optical signal; In combination with the second optical signal to form an output optical signal;
Comprising a method.   The method of claim 1, wherein forming the first and second optical signals comprises forming the first and second optical signals using an optical coupler.   The method of claim 1, wherein forming the first and second optical signals comprises supplying the first and second optical signals to first and second waveguides, respectively.   Supplying the first and second optical signals to the first and second waveguides, respectively, supplying the first and second optical signals to the first and second waveguides having substantially equal optical path lengths; 4. The method of claim 3, comprising:   Modifying at least a portion of the first optical signal using the plurality of non-guided electro-optical phase adjusting devices, subdividing the input optical signal using an optical demultiplexer; 5. The method according to any one of claims 1 to 4, comprising.   6. The method of claim 5, wherein the subdivision of the input optical signal comprises subdividing the input optical signal into a plurality of wavelength bands.   6. The method of claim 5, wherein modifying at least a portion of the first optical signal comprises providing the subdivided input optical signal to the plurality of non-waveguided electro-optical phase adjustment devices. The method described.   Modifying at least a portion of the first optical signal uses at least one of the plurality of non-guided electro-optical phase adjustment devices to subdivide at least one phase shift into the subdivided input optical signal. The method according to claim 7, comprising introducing into at least a portion of.   9. Modifying at least a portion of the first optical signal comprises multiplexing the subdivided input optical signal that includes at least one modified portion of the first optical signal. The method described in 1.   Forming the output optical signal comprises combining the first optical signal including at least one modified portion of the first optical signal with the second optical signal using an optical coupler; The method according to any one of claims 1 to 9.   Modification of at least a portion of the first optical signal using the plurality of non-waveguide electro-optical phase adjustment devices converts at least a portion of the first optical signal to the plurality of non-waveguide electro-optical phase. Providing to at least one of the adjustment devices and supplying at least one reflected portion of the first optical signal to at least one of the plurality of non-waveguided electro-optical phase adjustment devices; The method of claim 1. Optical demultiplexer,
An apparatus comprising: a plurality of non-waveguided electro-optical phase adjusting devices optically coupled to the optical demultiplexer; and a control device coupled to the plurality of electro-optical phase adjusting devices.   The apparatus of claim 12, wherein the optical demultiplexer, the plurality of non-waveguide electro-optical phase adjustment devices, and the control device are formed on a flat waveguide platform.   14. The apparatus of claim 13, wherein the planar waveguide platform is at least one of a polymer, silica formed on silicon, or a semiconductor waveguide platform. Each of the plurality of non-waveguide electro-optical phase adjustment devices includes:
First optical transmission medium,
Second optical transmission medium,
A slot designed to receive an electro-photoactive element disposed in the vicinity of the first and second optical transmission media; and at least a portion of the variable electric field disposed in the vicinity of the slot. An electrode designed to feed into said slot;
The apparatus of claim 12, comprising:   The apparatus of claim 15, wherein the slot has at least one curved edge.   The apparatus of claim 15, wherein the first optical transmission medium is a waveguide.   The apparatus according to claim 15, wherein the second optical transmission medium is a waveguide.   The device according to any one of claims 15 to 18, wherein the electro-photoactive element is at least one of liquid crystal and polymer-dispersed liquid crystal.   20. The controller according to any one of claims 12 to 19, wherein the controller is capable of supplying at least one signal indicative of a desired phase change to at least one of the plurality of non-waveguide electro-optical phase adjusters. The device described in 1.   21. Any of claims 12-19, wherein the optical demultiplexer is designed to provide light in a plurality of selected frequency bands to a corresponding plurality of non-waveguide electro-optical phase adjusters. A device according to claim 1.   The apparatus of claim 21, wherein the optical multiplexer is designed to receive light in a plurality of selected frequency bands from a corresponding plurality of non-guided electro-optical phase adjusters.   23. The apparatus according to any one of claims 12 to 22, further comprising an optical multiplexer optically coupled to the plurality of electro-optical phase adjusting devices.   24. The apparatus of claim 23, wherein the optical multiplexer is designed to combine light received in the plurality of selected frequency bands.   25. The apparatus of claim 24, wherein the optical demultiplexer and the optical multiplexer are a single device.   26. The apparatus according to any one of claims 12-25, further comprising a mirror optically coupled to the plurality of electro-optical phase adjusting devices.   27. The apparatus of claim 26, further comprising a wave plate disposed in the vicinity of the mirror and between the mirror and the plurality of electro-optical phase adjusting devices. First optical transmission medium,
Second optical transmission medium,
A first optical coupler for coupling portions of the first and second optical transmission media;
An optical demultiplexer coupled to the second optical transmission medium;
A plurality of non-waveguide electro-optical phase adjusting devices optically coupled to the optical demultiplexer;
An optical multiplexer optically coupled to the plurality of non-waveguide electro-optical phase adjusting devices;
An electro-optical device comprising: a third optical transmission medium optically coupled to the optical multiplexer; and a second optical coupler for coupling portions of the second and third optical transmission media Variable light filter.   29. The electro-optic tunable optical filter of claim 28, wherein the first, second, and third transmission media are waveguides.   30. The electro-optical variable optical filter according to claim 28 or 29, wherein the interferometer is formed on a flat waveguide platform.   31. The electro-optic tunable optical filter of claim 30, wherein the flat waveguide platform is at least one of a polymer, silica on silicon, and a semiconductor waveguide platform. Each of the plurality of non-waveguide electro-optical phase adjustment devices includes:
A first waveguide optically coupled to the optical demultiplexer;
A second waveguide optically coupled to the optical multiplexer;
A slot designed to receive an electro-photoactive element disposed adjacent to the first and second waveguides, and at least a portion of the at least one variable electric field disposed near the slot; Electrodes designed to feed into the slot,
32. The electro-optical variable optical filter according to any one of claims 28 to 31, comprising:   The electro-optical variable optical filter according to claim 32, wherein the electro-photoactive element is at least one of a liquid crystal and a polymer-dispersed liquid crystal.   34. The electro-optical variable optical filter according to any one of claims 28 to 33, further comprising a controller coupled to the plurality of non-waveguide electro-optical phase adjusters.   35. The controller of claim 34, wherein the controller is capable of providing at least one signal indicative of at least one selected phase change to at least one of the plurality of non-waveguide electro-optical phase adjusters. Electro-optical variable optical filter.   35. The electro-optic of claim 34, wherein the controller is capable of providing at least one signal indicative of at least one selected phase change such that the interferometer produces a filtered transfer function. Variable optical filter. First optical transmission medium,
Second optical transmission medium,
A first optical coupler for coupling portions of the first and second optical transmission media;
An optical demultiplexer coupled to the second optical transmission medium;
A plurality of non-waveguide electro-optical phase adjusting devices optically coupled to the optical demultiplexer;
An electro-optical variable optical filter comprising: a control device coupled to the plurality of electro-optical phase adjustment devices; and a mirror optically coupled to the plurality of electro-optical phase adjustment devices.   38. The electro-optic tunable optical filter of claim 37, wherein the first and second transmission media are waveguides.   38. The electro-optic tunable optical filter of claim 37, wherein the interferometer is formed on a flat waveguide platform.   40. The electro-optic tunable optical filter of claim 39, wherein the flat waveguide platform is at least one of a polymer, silica on silicon, and a semiconductor waveguide platform. Each of the plurality of non-waveguide electro-optical phase adjustment devices includes:
A first waveguide optically coupled to the optical demultiplexer;
A second waveguide optically coupled to the optical multiplexer;
A slot designed to receive an electro-photoactive element disposed adjacent to the first and second waveguides, and at least a portion of the at least one variable electric field disposed near the slot; Electrodes designed to feed into the slot,
41. The electro-optical variable optical filter according to any one of claims 37 to 40, comprising:   42. The electro-optical variable optical filter according to claim 41, wherein the electro-photoactive element is at least one of a liquid crystal and a polymer-dispersed liquid crystal.   43. The controller of claims 37-42, wherein the controller is capable of supplying at least one signal indicative of at least one selected phase change to at least one of the plurality of non-guided electro-optical phase adjusters. The electro-optical variable optical filter according to any one of the above.   44. The electro-electrical device of claim 43, wherein the controller is capable of providing at least one signal indicative of at least one selected phase change such that the interferometer produces a filtered transfer function. Optically variable optical filter.   The method of claim 1 substantially as herein described with reference to the accompanying drawings.   The apparatus of claim 12 substantially as herein described with reference to the accompanying drawings.

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